By the end of the year, we may finally solve one of the biggest mysteries in the gaming world: Why do red and blue Spartans hate each other so, so very much?

At Microsoft’s recent Spring Showcase 2012, we learned that 343 Industries has some grand plans for Halo 4, the sci-fi first-person shooter due out this holiday season for the Xbox 360. What are these plans? Heck if we know. The studio, who’s taking over franchise-development duties from Bungie, only teased us press guys with a few tiny morsels, never revealing much. But if you keep your eyes open, if you listen carefully, and if you talk to the right people, you might be able to glean a few juicy bits…like we did below.

Read on to see what we’ve discovered about Master Chief’s next adventure, and watch 343’s brand-new video documentary at the end of the second page to see if you can mine some more info from the elusive developers. Also check out our other news and previews from the Xbox 360 Spring Showcase.

1. The progression system won’t just be cosmetic

By earning enough experience in the Halo: Reach, you can unlock new shoulder pads, visors, visual effects, and other accessories for your online avatar. Too bad they really didn’t mean squat. “Armor upgrades — they were definitely aesthetic [in Halo: Reach],” says franchise development director Frank O’Connor. “And it works for a lot of people. I get an awful lot of [private messages] because I have some weird, fancy armor that people are obsessed with. So it matters to some people. But the reality is that they don’t have any impact on your game, other than it sometimes makes you a bigger target.”

That’s going to change with Halo 4, though details are non-existent at this time. “One of the things we wanted to do with Halo 4,” says creative director Josh Holmes, “was introduce a progression system that allows players to unlock things that not only change the way their character looks but also the way their character plays…that empowers players to make choices that have a meaningful impact on their gameplay experience in multiplayer. That’s a big change, but it’s one of the things we’re most excited about.”

2. On-screen icons will point out where weapon pickups are…for a special reason

New in Halo 4 are visual icons that point out which weapons are nearby (similar to Crysis 2 or Gears of War 3, only without the need to hold down a button to scan). This will be useful for newer players who haven’t yet memorized where every gun spawns, but it might also serve a deeper purpose, too. “We mark the shotgun for a reason,” says O’Connor. “There will be a very specific reason why the icon’s there that you’ll learn about later.”

3. Large feel-good text will tell you how you killed someone

In the brief demo that we saw, the words “Headshot kill!” or “Melee kill!” will flash on the screen when you’ve killed someone in the corresponding way.

4. Halo 4 will be higher resolution (but still not 60 frames per second)

Word is Halo 4 will run at a resolution of 1280×720, up a tad from Reach’s 1152×720. But if you’re hoping for Call of Duty’s silky smooth 60-frames-per-second speed, you’re out of luck. Halo 4 will remain at the series-standard 30 frames per second.

5. You’ll be able to customize loadouts

“You have the ability to choose from a wide arsenal of weapons and abilities that can be a part of your character’s individual loadout,” says Holmes. Right now, no one outside of 343 knows how much more ambitious this will be compared to what Reach offered.

6. Power weapons may not be on set timers

We’re hearing that power weapons may not respawn in at set intervals, adding some unpredictability as to when rocket launchers, Spartan Lasers, and WMDs may reappear on the battlefield. The point of this is to make sure experienced players won’t dominate matches by running timed circuits to grab all the best goodies.

7. A new bad guy

In the video below, the designers allude to a new danger in the Halo universe. “One of the things we wanted to do was really introduce a threat that is beyond anything that Master Chief has faced before,” says Holmes. “It also gives us an opportunity with that threat to add new gameplay,” says executive producer Kiki Wolfkill, whose name alone could take on that role.

What is this new enemy? We don’t know quite yet.

8. The return of Halo 3’s BR

“The battle rifle is back,” says lead designer Brad Welch in the vidoc. “It’s the old burst-fire precision weapon that [the fans] know and love.” It might be a fan-favorite, sure, but can players go back to it after having their hands on Halo: Reach’s beefier M392 DMR (Designated Marksman Rifle)?

9. Mechs?

This is more speculation than anything, but we wouldn’t be surprised if mechs make an appearance in Halo 4. One of the maps showed a Cyclops (previously seen in the real-time-strategy game Halo Wars) under construction (more on that below), and the developers kept referring to “big surprises” in store for the fans. Hmm…

10. The guy behind Call of Duty’s Nazi Zombies is working on Halo 4

Jessie Snyder, the game designer who invented Call of Duty’s cooperative-based Nazi Zombies mode, is on the Halo 4 team. That is enough to get this writer excited. Unfortunately, it doesn’t sound like he’s working on something similar for 343. His current role? Lead campaign designer. Bummer.

11. Multiplayer stages will tell their own stories

Instead of carving out sections of campaign stages to use as multiplayer maps, 343 plans on having dedicated arenas that will still tie into the story somehow. “One of the cool things with multiplayer is,” says Holmes, “these environments give us the opportunity to go to places in the universe that you might not otherwise encounter in our campaign. Places you’ve never seen before.”

“Warhouse is a civilian manufacturing plant that is traveling in near-space orbit above a gas giant,” says Holmes, describing the first revealed multiplayer map. “The outer area is set up with great flow, with man-cannons that allow you to launch back and forth. The center of this combat area is a weapons platform called the Cyclops Mark II that is being manufactured here. This forms a centerpiece for players to battle around, with lots of different entry points, different levels. You can move between them on catwalks and grav-lifts. Great flow, lots of action.”

“Wraparound is another smaller, symmetrical, arena-based map — but a very different space,” says Holmes. “This is a Forerunner solar facility within a Forerunner shield world that is creating the artificial sun that provides light and energy for that world. You’ve got catwalks with little drop-downs, a lot of quick movement between levels, lots of ramps to allow you to go back and forth. The outer circular corridor connects via different walkways to the center area. You’ve got these man-cannons as well that are positioned around the outer perimeter; they can launch players back into this central combat space where most of the action takes place. So this is another really fast-playing map that’s focused on our Team Slayer experience for Halo 4.”

OK, that’s great and all, but here’s the most important quote we’ve heard from the developers:

“We’ve created a fairly compelling and fairly convincing reason why red Spartans can fight blue Spartans,” says O’Connor.

You don’t say….